Can lack of sleep make you fat?

Yet another clinical study has confirmed the growing body of evidence linking inadequate sleep to obesity.

One of the more surprising factors linked to weight gain is lack of sleep. More and more research studies are finding that poor sleep patterns and insufficient sleep are closely linked to weight gain and obesity.

The mechanism linking poor sleep to weight gain is not entirely understood, but is likely related to how signals from the brain which control appetite are altered by sleep restriction. Inadequate sleep can alter the levels of the appetite-stimulating hormone ghrelin while reducing production of the fullness-feeling hormone leptin. This can lead to increased food consumption without a similar increase in energy expenditure.

Much of the sleep research though has involved either observational studies looking at habitual sleep patterns and body weight, or single-night studies done in a controlled sleep laboratory. Now researchers have extended the research to look at how 5 nights of poor sleep can affect energy expenditure and hormone levels with the results published in the journal PNAS[3].

Sixteen healthy adults took part in the study. Their average normal night’s slumber was just over 8 hours and all were at a healthy body weight with no heavy users of alcohol or caffeine and none were taking medications.

The sleep deprivation conditions involved making participants wait 2 hours past their normal bedtime before being allowed to sleep and rousing them from their slumber 2 hours earlier than normal. This was repeated for 5 days in a row under controlled laboratory conditions where energy expenditure, diet and blood tests were carefully monitored.

The poor sleep patterns did result in a small increase in energy expenditure of around 5% which at first blush seems positive. Yet this was more than offset by a higher amount of food eaten, especially after dinner at night time, which caused an average weight gain of 0.82 kg over just 5 days.

What surprised the researchers was that changes in hormone levels were in favour of blunting food intake, yet despite this, overeating still occurred. One theory to explain this is that it was the change in the circadian rhythm resulting in more hours of wakefulness that altered the normal eating pattern.

Showing that weight gain is not set in stone, when the participants reverted back to a normal sleep pattern, they ate less food and a small amount of weight loss seen.

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What it all means
Sleep plays an important part in energy metabolism. Disruption of a healthy sleep cycle can throw the body out of kilter, resulting in more food eaten and more weight gained. For someone that is struggling to control their weight, it may pay to look more closely at how they prioritise quality sleep in their life.

Tim

Confused about the mixed soup of nutrition messages being stirred through the media? Tim maintains an active nutrition blog at www.thinkingnutrition.com.au[5] where you'll find the latest nutrition research and controversies discussed in straight forward language, distilling out what you need to know for your better health